Previously existing directional LED lamps including a lens disposed downstream of at least one light-emitting diode generally have a fixed emission angle of the light beam emitted by them. Emission angles of between 10° and 60° are customary in this case. The chosen emission angle typically depends on the application. In this regard, for example, a wide emission is often desired for room lighting, whereas a narrower emission is usually desired for lighting objects.
A halogen lamp retrofit lamp (Bulbrite LED MR-16 Multibeam) exists which has an emission angle adjustable in steps of 15°, 20°, 25°, 30°, 35°, and 40°. In this case, a distance between the light-emitting diode (LED) serving as light source and a lens disposed downstream of the LED is set by means of a mechanism. What is disadvantageous about this concept is the use of a traditional lens having a small diameter, which prevents large collimation strengths in conjunction with a compact design.
An incandescent lamp retrofit lamp (LUMITRONIX XR20 LED Spot) is known which can optionally be equipped with a diffuse or a clear lens. This leads to a softer or sharply delimited light spot, but not to a significant change in the emission angle.
Fresnel lenses are known, having Fresnel rings as a light deflection structure at their light entrance surface, at which rings entering light can be deflected (refractively) in the direction of the light exit surface by means of simple light refraction.